1. Field of the Invention
This invention relates to apparatus and methods for migrating data in a tiered storage architecture.
2. Background of the Invention
In today's tiered storage architectures, the “hotness” or “coldness” of data may be continually monitored so that it can be optimally placed on storage media. For example, “hot” (i.e., frequently accessed) data may be placed on faster, more expensive storage media (e.g., solid state drives) to improve I/O performance. “Cold” (i.e., less frequently accessed) data may be placed on slower, less expensive storage media (e.g., hard disk drives) with reduced I/O performance. As the temperature of the data changes, the data may be migrated between storage tiers to optimize I/O performance.
In tiered storage architectures, determining when to migrate data as well as what data to migrate is a significant issue. Some tiered storage architectures may promote an entire file or dataset to higher performance storage media even though only portions of the file or dataset are accessed on a regular basis. This may utilize the higher performance storage media in an inefficient manner and potentially displace more frequently accessed data from the higher performance storage media.
The timing associated with migrating data may also be an important issue, since it may significantly affect I/O performance. In some cases, migrating data to higher performance storage media when the data is in high demand may significantly reduce I/O performance and throughput during the migration. Migrating data at inopportune times may be self-defeating as the goal of the migration may be that of ultimately improving I/O performance.
In view of the foregoing, what are needed are apparatus and methods to more optimally migrate data in tiered storage architectures. Ideally, such apparatus and methods will improve I/O performance and throughput by more optimally addressing when to migrate data and what data to migrate.